Obturator for guns



' Oct. 7, 1947. w. SUMMERBELL ET AL 2,428,398

' OBTURATOR FOR GUNS Filed April 11, 1945 l k W 72 W1 m 1% E dmnfi m n 6@mm M md mm Patented Oct. 7, 1 947 UNITED STATES oFFicE OBTURATOR FORGUNS l i illiarn Summerbell, Washington, D. (2., Louis J. Rhein,Aberdeen, Md., and Owen D. Hoopes,

Arlington, Va.

1 Claim.

The invention described herein may be manufactured and used by or forthe Government for governmental purposes, without the payment to us ofany royalty thereon.

Our invention relates to obturators of the character adapted for usewith a breech loading gun of the separate loading type wherein a primercartridge is fired through a passage in the obturator to ignite andfunction the main propelling charge.

One of the problems long existing in firing guns of this character hasbeen how to prevent injury to the spindle plug caused by the pressure ofgases of the main propelling charge. The force of these gases, escapingrearwardly through the flash passage is very great and difficulty hasbeen experienced in preventing these gases from escaping through theprimer chamber, around the primer cartridge, thereby causing injury tothe spindle plug necessitating frequent replacement, and also causingburning and warping of the primer cartridge case. It is, therefore, theprincipal object of our invention to provide an obturator for preventingthe escape of such gases by providing sealing means for effectivelyconfining the gases within the primer cartridge and the flash passageleading thereto, and preventing their rearward escape around the primercartridge. This result is eifected in part b crimping the lips of theprimer cartridge upon insertion by forming an inwardly inclined,constricted portion in the inner end of the primer chamber. In additionmeans are provided for using the pressure resulting from the burningpropellant gases for efiectively pressing the side walls of the primercartridge case tightly against the inner walls of said constrictedportion, thus providing a substantial seal and thus preventing saidpropellant gases from escaping through the small space that wouldnormally exist between the primer case and the walls of the primerchamber. Since the gases rush into the space inside the primercartridge, the expansion of the gases therein will tend to expand thecartridge walls, thereby facilitating the sealing of the space betweenthe primer cartridge and the walls of the primer chamber. Heretofore, ithas been the practice to terminate the flash passage adjacent to theentrance to the primer chamber, and by this arrangement, the pressure ofthe gases was, partially at least, rearwardly against the lips of theprimer cartridge and a portion of such gases frequently escaped betweenthe walls of the chamber and the primer cartridge, resulting in thedamage above referred to. By the use of our obturator the problem hasamended April 30, 1928; 370 0. G. 757) been solved, resulting in aconsiderable saving of time in changing spindle plugs and avoiding theconsequent loss of fire power while the change was being made, as Wellas a saving of material.

With the foregoing and other objects in view, as will hereinafter morefully appear and as will be more particularly pointed out in theappended claim, reference is now made to the accompanying drawingforming a part of this application, in which:

Figure 1 is a horizontal, longitudinal sectional view, taken through aportion of an obturator, illustrating our improved mechanism.

Figure 2 is a detail perspective View of a baffle member employed in theinvention, and

Figure 3 is an end view of Figure 2 taken a ong the lines 3-3.

Referring now to the drawing, a portion of an obturator is showngenerally at it. An obturator spindle i2 is slidably mounted in abreechblock l2" and has its rearward end 14 provided with externalthreads I5 for threadabl engaging matching threads I8 formed in a recess2!] at the forward end of a firing mechanism housing 22. The spindle I2is held in the breechblock i2" by a helical spring 22 having one endseated on a washer I2 in the breechblock l2 and the other end bearingagainst a lock ring l8 keyed on the spindle l2 and abutting the firingmechanism housing 22. The housing 22 and the lock ring l8 are heldagainst relative rotation by a pin l8" carried by the housing 22 andprojected into the lock ring I 8'.

The spindle l2 has a central longitudinal bore or flash passageway 24leading at its opposite or forward end, not shown, to the breech end ofthe barrel bore of the gun where is located the usual propelling charge.The housing 22 has a longitudinal bore 26 in which is located a spindleplug 28 the reduced rearward portion 38 of which extends into thereduced rearward portion 32 of bore 26 and the reduced threaded forwardportion 34 of which threadably engages the inside of an enlarged annularthreaded recess 36 in the rearward portion M of spindle I2.

The spindle plug 28 has a central longitudinal bore 38, the rearwardportion 49 of which is of an inside diameter sufficient to receive aprimer cartridge case 42. The primer 42 usuall contains a black powdercharge with a percussion sensitive material such as mercury fulminate,and a quantity of beeswax for closing the forward end of the primer. Forpurposes of clarity and because the individual designs of these primersmay vary, the internal construction has not been il- 3 lustrated. Theside walls 43 and 44 of the end 40 of the bore 38 are very slightlyinwardly tapered from rear to front for the greater part of the lengthof the primer cartridge case 42, up to a location 46 from which locationthe said side walls converge slightly inwardly at a greater rate to thelocation 48 so that as the primer cartridge case is pressed into thebore 40, its forward lips 50 are crimped inwardly as indicated, thusmaking for a tighter fit of the lips of the cartridge.

case within the bore 40 particularly from location 46 to location 48.The degree of convergence of the bore 40 from location 46 to location 48has been exaggerated in the drawing for purposes of clarity ofillustration only.

The forward portion 52 of central bore 38 is enlarged and has tightlyfitted therein a hollow cylindrical member or baflie 54 made ofcorrosion resisting steel or other suitable'material. The bafile 54 hasa central bore 56 equal in diameter to and axially aligned with bore 24of spindle l2. An annular copper washer 58-having a central hole islocated in the space at the inner or forward end of the recess 36 asshown. Members 28 and 54 have at their forward ends, projecting circularportion 60 and 62 respectively, which are V-shaped in cross section. Theinner surface of recess 36 has a circular projection 64 also'V- shapedin cross section. These projections 66, 62 and 64 are pressed intocopper washer 58as the surrounding members are drawn together, thusenhancing the sealing eilect. of the washer 58 against escapeof gasesaroundit.

As shown in the drawing, the rearward end surface of baffle 54extendsradially inward from cations, 66 to 68 andtheninclinesconvergently inwardly toward location 10 whence itextends radiallyinward tothe inner surface of bore 56-at location l2. It will be noted,as illustrated, that the lips 50 of primer cartridge case 42 do nottouch baffle 54 at any point, although the primer cartridge case 42 isfully inserted into bore 40 as far as it is supposed to go. It .willalso be noted, as illustrated, that the rearwardly extending lip 14 ofbaliie 54, that is, the portion extending rearwardly of location 58extends rearwardly by a distance sufficient to extend slightly insidethe lips 50' of primer cartridge case 42 but not touching them.

By means of the construction illustrated and described, it has beenfound that the gases from the burning propellant, which rush rearwardlythrough passageway 24 and bore 56 do not escape around. the outersurfaces of primer cartridge case 42,. but are effectively sealed inagainst escape by this route.

Thus. the gases-rush rearwardly into the interior ofthe primer cartridgecase 42 and, due totheir great, pressure the serve to. expand the primeroutwardly .against the walls of. bore 40' sealing the gases fromescapingbetween the outer surface of the primer and the inner surface of bore40.. Thenthe rearwardly rushing gases change direction andreachtheregion between the outer sloping surface of the annular lip 14of bafile 54 and the extreme forward end of. lips 5|] of the primercartridge case 42, but by this time the primer walls, have been expandedso tightly against bore 40 that the gases cannot escape around theprimer.

In prior obturators, not using this invention, there has beenconsiderable burning and warping of the primer cartridge case outersurface and the inner wall of the bore,40., However, by use of theinvention described herein, this diificulty has been overcome.

The primer cartridge case 42 is firmly held in place with its sideswithin the bore 40 as indicated, and its rim 16 resting against andwithin a recess 18 formed in the rearward end of a hollow cylindricalextractor 19 the sides 80 of which are slidably located'in the spacebetween the inner surface of bore 32 and the outer surface of rearwardportion 30 of spindle plug 28. Any suitable means, such as a movableblock 82 which is diminutive as compared to the breech block of the gunis used for pressing primer cartridge case 42 into bore 40' and holdingit there while the gun is fired. The construction of the extractor I9and breech block 82.;is the subject of andis more fully described andillustrated in ourcopending patent application, Serial No.604,286,,filed-July 10, 1945, entitled Firing mechanism.

While the invention has been described in specific terms, it is to beunderstood that various changesmay be made inthe shape, size, materialsand. arrangement without departing from the spirit and scope of theinvention.

We claim:

An obturator for use in breech loading guns of the separate loading.type, comprising an obturator spindle havinga fiash passagetherethrough, a plugin the rear end of said spindle provided withaprimer cartridge chamber having a tapered front endto contact the frontend of a primer cartridge whensaid cartridge is fully inserted in saidchamber, means carried by the plug forward of said chamber and protrudintherein to direct the gases from the propellant charge of the gun toexpand the forwardend of a cartridge case into gas sealing contact withthe tapered portion of the chamber to block the passage of the gas frombetween the outer surface of the primer case and the inner wall of saidchamber, said means comprising a bafile member in the plug having aflash passage therethrough communicating with the primer cartridgechamber and havingan annular lip on its rear end, surrounding thepassage through. said baffle member extending into the open end of thecartridge case and constructed and arranged to direct the gases into thecartridge case chamber.

WILLIAM SUMMERBELL.

LOUIS J RHEIN.

OWEN D, HOOPES.

REFERENCES CITED Thefollowing references are of record in the file ofthis patent:

UNITED STATES PATENTS

